The invention provides a novel heat exchanger. The novel heat exchanger comprises a first tube box, a shell pass part and a second tube box which are connected in sequence as well as a tube bundle arranged in the shell pass part; the first tube box comprises an end socket, a drum body short joint and a device flange which are connected in sequence; the second tube box comprises an end socket, a connecting tube and a clamping flange; the shell pass part comprises a first flange, a shell pass drum body and a second flange; the tube bundle comprises a first tube plate, a heat exchange tube and a second tube plate, and the two ends of the heat exchange tube are respectively connected onto the first tube plate and the second tube plate. Compared with the existing single tube pass floating head heat exchanger, parts such as a hook ring, a floating head flange and the like are removed, a connecting manner of one side tube plates is changed, a tube pass outlet is not required to be formed from the shell pass, and the structure of the heat exchanger is simplified, such that the novel heat exchanger is more convenient to mount and overhaul, and the device cost is reduced.